Exemplary embodiments of the present disclosure relate to a gas turbine, and more particularly, to a method for replacing a bearing covering the outside of a tie rod installed in a gas turbine.
In general, a gas turbine refers to a type of internal combustion engine that converts thermal energy into mechanical energy by the expanding high-temperature and high-pressure combustion gas in a turbine. The high-temperature and high-pressure combustion gas is generated by burning a mixture of air and fuel, the air being compressed to high pressure by a compressor. The compressor and the turbine are driven by rotational force through a rotor.
The gas turbine includes a plurality of compressor rotor disks each having a plurality of compressor blades arranged on the outer circumferential surface thereof, the components of which make up a compressor rotor and a turbine rotor.
The gas turbine uses a tie rod for not only connecting the compressor rotor disks to each other such that the compressor rotor disks are rotated together, but also for connecting a plurality of turbine rotor disks to each other such that the turbine rotor disks are rotated together, the plurality of turbine rotor disks each having a plurality of turbine blades arranged on the outer circumference thereof. Since the tie rod is extended through the centers of the compressor rotor disks and the turbine rotor disks, the compressor rotor disks and the turbine rotor disks can be stably fastened.
Recently, however, the increase in size and efficiency of gas turbines have increased the whole lengths of the gas turbines. Therefore, the support for the tie rod, which is rotated at high speed with the compressor rotor and the turbine rotor of the gas turbine, may become destabilized. Furthermore, the turbine rotor has a bearing mounted therein, in order to guarantee a stable rotation through the rotation of the tie rod.
The tie rod extends through the compressor rotor having a plurality of compressor rotor disks installed therein and the turbine rotor having a plurality of turbine rotor disks installed therein. In particular, it is not easy to install a unit for stably supporting the rotating tie rod in a space where combustors are radially arranged at the outer circumference between the compressor rotor and the turbine rotor along the center axis of the gas turbine.
The bearing needs to be replaced after being used for a predetermined period. In order to replace the bearing, heavy equipment such as a crane must be used to lift the rotor. In this case, it is difficult to precisely control the crane.
For example, the outside of the bearing is covered by a bearing housing, and a gap between the bearing and the bearing housing is just a few millimeters. Therefore, when the crane is not precisely controlled, the neighboring parts may be damaged or broken. Thus, safety is inevitably lowered.